A WORK IN PROGRESS
In, B.C. a bluebirds translocation and repopulation program in the Cowichan Valley struggles, despite a promising start
EACH SPRING, MEMBERS OF THE COWICHAN VALLEY
Naturalists’ Society eagerly await the return of the “flying blue jewels.” It’s a name they have applied to the tiny population of formerly extirpated western bluebirds
(Sialia mexicana) that now live in the valley. The society is hoping it will eventually grow into a self-sustaining breeding population on southeastern Vancouver Island and the southern Gulf Islands. These beautiful migratory songbirds are famed for their ability to evoke happiness and wonder, and that holds true in the Cowichan. “Anyone who sees them gets very excited. They inspire a real sense of joy and an appreciation of nature,” says Hannah Hall, a biologist with the society.
Western bluebirds are small thrushes that spend much of their lives close to the ground. Often seen perching on tree limbs and fence posts, they like to hover low over open fields where they hunt for their food. Upon seeing an insect, they will quickly drop to the ground to snatch their prey. Males have brilliant blue plumage and rust-coloured breasts, a colour combo that caused renowned naturalist W.L. Dawson to exclaim in 1903, “Reflecting heaven from his back and the ground from his breast, he floats between sky and earth like the winged voice of hope.”
Western bluebirds breed throughout much of the western United States and Mexico and were also once widespread across southwestern British Columbia. But the Vancouver Island population totally disappeared in the mid-1990s, the victims of a lethal trifecta: ongoing loss of habitat, competition for nesting sites from growing sparrow and starling populations, and predation by raccoons and cats.
In 2012, a five-year project called Bring Back the Bluebirds was launched to re-establish western bluebirds at the Cowichan Garry Oak Preserve near Duncan, B.C. The Garry Oak Ecosystems Recovery Team, working with the Nature Conservancy of Canada, organized the construction of nest boxes, the engagement of landowners and the “sourcing” of birds. The birds were drawn from a healthy population of some 600 western bluebirds that inhabit the sprawling Fort Lewis-mcchord military reserve near Olympia, Washington.
The goal of the Cowichan project, which was based on a similar five-year reintroduction of bluebirds to Washington State’s San Juan Islands in 2007, was to translocate 90 bluebirds to the Cowichan Valley. Ultimately, only 65 were imported over four years because of bureaucratic snarls and health concerns. After reaching a high of 28 returning adults and 67 fledglings in 2016, the project was handed over to the Cowichan Valley Naturalists’ Society. It currently has about 25 volunteers actively engaged in the venture, plus two paid employees, project coordinator Hall and wildlife technician Braden Judson.
All told, the society maintains 250 nest boxes on 18 different trails, all thanks to the support of 70 landowners. These nest boxes also provide homes for swallows, wrens and chickadees. Local volunteers donated 3,000 hours to the project in 2018, including the work of 15 trail monitors and five others who feed the birds mealworms each spring. In a good year, the bluebirds can rear two broods of four to eight babies that stay in the nest for about 20 days before fledging.
In addition to restoring bluebirds to their former haunts, the project aims to help preserve the Garry oak ecosystem in which the birds live. This unique habitat of gnarled oaks and open meadows supports a wide range of wildflowers, grasses, shrubs, lichens and fungi, as well as a variety of animals. It is one of Canada’s most endangered ecosystems — only three per cent of native Garry oak ecosystems remain in a natural state in B.C.
Although the Bring Back the Bluebirds project has enjoyed strong local support and the volunteers have perfected their techniques, the birds are struggling. In 2018, the population totalled 12 birds that produced nine successful nests and 42 fledglings. This year, only nine of the banded birds returned from their migrations to Oregon and California. The small population is a concern, as the survival of the birds remains vulnerable to inclement weather and skewed male-to-female reproductive rates.
“The pattern in the Cowichan seems to be following what happened in the San Juan Islands. Soon after we stopped doing translocations there, the population crashed from 36 birds to three,” says Gary Slater, an avian ecologist with the Center for Natural Lands Management in Olympia, Washington, who has been involved in both projects.
Although reproductive rates at the Cowichan and San Juan sites match those at the military base, the adult birds are not returning at the same rate from their migratory travels. Slater believes that more translocations will have to be done to sustain the populations. “Ideally, we would like to move as many birds as we can into the Cowichan Valley and also introduce bluebirds to other sites in the area, such as Whidbey Island and the Saanich Peninsula.” In fact, biologist Hannah Hall says the Cowichan Valley Naturalists’ Society is now raising funds to import more bluebirds from Washington in the spring of 2020.
As Slater notes, “The translocation of songbirds is a new scientific field, and we’re still trying to determine which methods succeed and which ones fail. There’s more work that needs to be done.”